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    <title>Document</title>
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<script>
  
  let arr = [{a:1,b:2,c:'1:2'},{a:66,b:99},{a:'哈哈',b:'呵呵',c:'7:9'}]
  //执行三次:
  //第一次:prev->[]                      next->{a:1,b:2,c:'1:2'}             [{attrId:1,valueId:2}]
  //第二次:prev-> [{attrId:1,valueId:2}]  next->{a:66,b:99}                  [{attrId:1,valueId:2}]
  //第三次:prev->[{attrId:1,valueId:2}]   next->{a:'哈哈',b:'呵呵',c:'7:9'}   [{attrId:1,valueId:2},{attrId:7,valueId:9}]
  let result = arr.reduce((prev,next)=>{
         if(next.c){
           let [attrId,valueId]   = next.c.split(":");
           prev.push({attrId,valueId});
         }
         return prev;
  },[]);
  console.log(result);
</script>